Tranny Question

mopar Joe 65

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I had my trans. rebuilt about a year ago and it works great but I have a leak somewhere I think its the pan gasket anyway I am going to take it back to the rebuilder an get it sealed. I was just wondering what type of fluid I should use in it ? When they rebuilt it I put ford type f in it I got from o’reilly’s. It’s a 68 727 TF Should I use something more common to find ? Thanks for any advice.
 
On a rebuilt transmission, you can use ATF-4, a full synthetic. On a well used transmission stick with ATF-3. Ford type transmission oil can be used if a firmer shift is desired for performance applications. For street use stay with ATF-3 or ATF-4. The Ford type fluid has a much shorter life.

Dave
 
And it’s what the factory used in them.

C98DF033-D3DA-43B5-9ECB-5585693B4475.png
 
In many cases, the atf for Dexron/GM applications is now marketed as "Multi-Make" in many brands, just as the Honda atf is marketed as "Multi-Make" also. SO it is very important to read the back of the container to determine the base application is for GM Dexron III (or some Ford Mercon V) applications.

In the ACDelco Chemical Catalog, seems like it is termed "Type III" as GM no longer licenses "Dexron III" atf as it was replaced by Dexron VI atf in many newer-gen 5+ speed automatic transmissions. GM claims Dex VI is backward compatible all the way to 1949, but Dex III is NOT upward compatible on the newer-than 4-spd "clutch-to-clutch shifting" automatics.

Ford does not license "Type F" atf any more, either. It can be harder to find than the old Type A Suffix A "clear" atf that Dexron replaced.

Enjoy!
CBODY67
 
I would use the Mopar ATF +4 just because it's a modern synthetic of high quality and would be easy to find anywhere. Just be careful that you don't mix it with the old Dexron because I heard they're not compatible. And make sure that if you replace the pan gasket you use the genuine OEM Mopar gasket. The cork ones are junk.
 
I would use the Mopar ATF +4 just because it's a modern synthetic of high quality and would be easy to find anywhere. Just be careful that you don't mix it with the old Dexron because I heard they're not compatible. And make sure that if you replace the pan gasket you use the genuine OEM Mopar gasket. The cork ones are junk.
If the rebuilder is only going to drain, seal, and fill, the type f is going to remain in the transmission. I think the issue is: what is compatible with type f?

Post 12 in this thread says that dexron and ford type F are compatible. I think ATF+4 is only compatible with other ATF+.
Is it ok to mix Type F and Dexron?.
 
Might not mix Type F and any other fluids as the friction modifiers which make each one what they are are not the same. Type F has a higher initial "bite" and then "the bite" tapers off until full lock-up of the frictions happens, which results in the firmer shift, whereas the Dexron family fluids have less "bite" (for a bit more slippage upon initial engaagement of the frictions, though not real slippage per se) for a smoother shift feel. With the ATF-family fluids being different to allow the advanced electronics in the newer Chrysler automatics to do their thing and not cook themselves.

Back when the UltraDrives came out, the orig fluid spec was Dexron III + the Chrysler additive, but that was later changed to the "ATF-family" Chrysler-spec fluids. Without the additive, it was alleged that the UDs would later fail from slippage the trans controller could not fix.

In one of the old bulletin boards on the Internet, the Chrysler board (run by Dr. David Zatz) noted that Dexron fluids are allegedly "used up" after about 40K miles (only place I'd read that) and that ATF+3 was a superior fluid for longevity and semi-syn to be compatible with the internal seals of the older TFs and such. Then ATF+4 arrived to supercede it. So, no question that ATF+4 is a great atf, but their MIGHT be some incompatibilities with some lip seals and such, in the long run. Now, as time has progressed, I suspect that almost all of the transmission parts vendors have evolved into full-syn-compatible seals and such, so that issue might not be operative any more . . . unless the rebuild kit is NOS?

BUT, if the builder prefers Type F atf and has configured the frictions that were used to be compatible with it AND it causes no issues with lip seals and such, then I feel that should be whas is used in the transmission. As popular as it was in the performance market back then, in non-Ford automatics, I heard nothing about it causing any issues when it replaced Dexron in GM or other automatic transmissions.

As far as the pan gaskets, I suspect that any rubberized-cork gasket (OEM-spec Chrysler, etc.) can work well IF you add a skin coat of high-heat black silicone sealer on all sides and edges of it, letting it cure overnight, before installation. Just a thin coat spread out with a protected finger tip. This seals the rubberized-cork and prevents the lighter parts of the fluid from wicking through the cork parts of the gasket over time. It's worked well for me on ALL engine and trans pan gaskets for decades. Then ensure that the trans oil pan is FLAT with no indents where the bolts go through it. Snug-down the bolts with no excessive torque.

If you might desire to "get fancy", you can get a battery-powered extracctor unit to suck the atf out through the filler pipe. Amazon, eBay, and possibly Home Depot have them to do similar for changing the engine oil in mowers and such. Not very expensive, last time I checked. Just need an empty container(s) to put the old oil into for recycling. This way, no need to drop the pan for a fluid change.

IF some higher-temp resistance might be needed, seems like there might be some synthetic Type F fluid available somewhere, just as there used to be synthetic Dexron III atf.

Just some thoughts,
CBODY67
 
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Cork pan gaskets work good.

the black runner pan gaskets dnot seal.

make sure the pan is flat

make sure nothing above the pan is leaking.
 
On my son's 70 Fury and my 73 Suburban, the transmission had a persistent leak at the back near the tail-shaft. The pin for the rear-band anchor on both cars was leaking. The pin is sealed with two O-rings. On the wagon, I removed the pin and installed two new O-rings and sealed with a a bit of RTV. On the 70 Fury, it was more of an on-the-fly repair. Generously doused with carb-cleaner, air dried, and spread RTV around the circumference of the pin, then added a round piece of Rubber gasket, sealed with RTV. Other possible sources of leaks are the adjuster screws for the front and the rear bands, and the cooling line fittings.

transmission pics Rear band.JPG
 
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